1. Field of the Invention
The present invention relates to a wobble plate type refrigerant compressor having a non-rotatable wobble plate supported on a rotatable drive element via a wobble plate support including a thrust bearing assembly. More particularly, the present invention relates to a thrust bearing assembly for a wobble plate support adapted for a wobble plate type compressor, which assembly functions to reliably support a non-rotatable wobble plate on a rotatable drive element while holding an assembly of roller elements and an annular retainer element of the thrust bearing assembly in position to resist a thrust force acting on the wobble plate due to reaction of pressure of a refrigerant gas compressed by reciprocatory pistons.
2. Description of the Related Art
Japanese Unexamined Utility Model Publication No. 62-88887 discloses a wobble plate type compressor having a drive shaft receiving a drive force from outside of the compressor, a rotatable drive element mounted on the drive shaft and having a drive face inclined with respect to a plane vertical to the axis of the drive shaft, a non-rotatable wobble plate supported on the drive face of the rotatable drive element via a thrust bearing assembly, a plurality of compression pistons reciprocated in a plurality of cylinder bores of a cylinder block by the wobble plate, and piston rods for compressing refrigerant gas of an air-conditioning or refrigerating circuit. The wobble plate is held on a ball-bearing and is able to wobble thereabout when driven by the drive element, and rotation thereof is prevented by a bevel gear engagement arranged between the wobble plate and an end of a ball-support shaft mounted in the cylinder block. The wobble plate is also resiliently urged by a spring element axially toward the drive face of the drive element. The thrust bearing assembly supporting the non-rotatable wobble plate on the drive face of the rotatable drive element is arranged to resist the above-mentioned resilient force of the spring element and an axial reaction force acting on the wobble plate due to compression of the refrigerant gas by the pistons, and includes a plurality of roller elements and a retainer element for retaining the roller elements in position while preventing a radial displacement thereof. The thrust bearing assembly is held between the inclined drive face of the drive element and the wobble plate by a pair of annular guide races attached to the ends of the drive element and the wobble plate. Namely, the annular guide races not only allow the roller elements to perform a stable rolling operation but also regulate the movement of the retainer element.
In accordance with the above-mentioned arrangement for supporting the non-rotatable wobble plate, an unfavorable state of the wobble plate occurs during the operation of the compressor such that the wobble plate is displaced and separated from the drive face of the drive element in a direction corresponding to a direction of the piston motion when compressing the refrigerant gas against the above-mentioned spring force and the high refrigerant gas pressure transmitted via the pistons, due to a large inertia of the wobble plate per se accompanying the wobbling motion of the wobble plate. As a result, a distance between the drive face of the drive plate and the wobble plate is increased, and therefore, the thrust bearing assembly is not adequately held between the drive face of the drive plate and the wobble plate. Namely, when the distance between the drive face of the rotatable drive element and the wobble plate is increased, the pair of guide races fail to adequately guide the thrust bearing assembly, and the retainer element of the thrust bearing assembly carries out an unregulated movement between the drive element and the wobble plate. Consequently, the retainer element is damaged or broken due to wear thereof, resulting in a breakage of the roller elements of the thrust bearing assembly. Particularly, while the compressor is performing a high speed operation, the above-mentioned separation of the wobble plate from the drive face of the drive element often occurs and becomes a cause of damage to or breakage of the thrust bearing. This is therefore fatal to the reliability of the operation of the wobble plate type compressor, especially in a high speed operational range of the compressor. On the other hand, since the internal construction and arrangement of the wobble plate type compressor are complicated, it is impossible to prevent an occurrence of the separation of the wobble plate from the drive element over the entire operational range from a low speed operation to a high speed operation of the compressor.